Signal valve

ABSTRACT

The signal valve indicates when a piston, movable in a cylinder, is moved to one end of the cylinder. The signal valve includes a housing mounted on the cylinder and having first and second passageways therein which communicate with the interior of the cylinder through first and second ports in the side wall of the cylinder. The first passageway extends through the housing between the first port and a fluid pressure sensing device. The second passageway terminates within the housing. A valve member is positioned for movement within the housing and has a first end adapted to close the first passageway and a larger second end. When the same pressure is acting on both ends of the valve member, the force on the second end is greater than the force on the first end to move the valve member to close the first passageway. When the piston is moved to one end of the cylinder between the ports, the fluid pressure acting on the piston is admitted through the first port into the portion of the first passageway between the first port and the valve member to establish a force on the valve member for moving the valve member to open the first passageway to permit operating fluid to flow through the first passageway to indicate that the piston is at the one end of the cylinder. A vent passage in the housing vents the portion of the first passageway in communication with the pressure sensing device when the first passageway is closed by the valve member.

United States Patent Wright 51 Mar. 14, 1972 [54] SIGNAL VALVE Lee A.Wright, Kettering, Ohio [73] Assignee: Mosier Industries, Inc., Dayton,Ohio [22] Filed: Mar. 9, 1970 [21] Appl. No.: 117,746

[72] Inventor:

FOREIGN PATENTS OR APPLICATIONS 585,819 10/1933 Germany ..91/403 PrimaryExaminerEdgar W. Geoghegan Assistant Examiner-lrwin C. Cohen [S 7]ABSTRACT The signal valve indicates when a piston, movable in acylinder, is moved to one end of the cylinder. The signal valve includesa housing mounted on the cylinder and having first and secondpassageways therein which communicate with the interior of the cylinderthrough first and second ports in the side wall of the cylinder. Thefirst passageway extends through the housing between the first port anda fluid pressure sensing device. The second passageway terminates withinthe housing. A valve member is positioned for movement within thehousing and has a first end adapted to close the first passageway and alarger second end. When the same pressure is acting on both ends of thevalve member, the force on the second end is greater than the force onthe first end to move the valve member to close the first passageway.When the piston is moved to one end of the cylinder between the ports,the fluid pressure acting on the piston is admitted through the firstport into the portion of the first passageway between the first port andthe valve member to establish a force on the valve member for moving thevalve member to open the first passageway to permit operating fluid toflow through the first passageway to indicate that the piston is at theone end of the cylinder. A vent passage in the housing vents the portionof the first passageway in communication with the pressure sensingdevice when the first passageway is closed by the valve member.

Attomey-Greist, Lockwood, Greenawalt & Dewey 4 Claims, 2 Drawing Figures104 116 1s 08 I5 20 1 76 l 1 2 m 28 y 54 M 24 Mk "l6 C 6 IO PatentedMarch 14,, @1111 I 3,648,568

IN VENTOR LEE A. WRIGHT ATT'YS.

SIGNAL VALVE The present invention relates to a signal valve forindicating when a piston, movable in a cylinder, is moved by thepressure of an operating fluid to one end of the cylinder. Morespecifically, the present invention is directed to a signal valve whichcan be used for monitoring or controlling the movement of a piston in acylinder, such as the piston in a pneumatic piston and cylindermechanism. For example, in one application, the signal valve of thepresent invention can be utilized for monitoring the movement of apiston in a cylinder by operating a whistle or other fluid pressureoperated, signal producing mechanism which produces a signal indicatingthe piston is at one end of the cylinder. In another application, thesignal valve can be utilized to send a signal to a control system whichcontrols the flow of pressurized fluid to either end of the cylinder. Inthis respect, a group of piston and cylinder mechanisms, each with asignal valve of the present invention mounted at each end of eachcylinder, can be controlled by a control system which, upon receivingappropriate signals from the signal valves, will cause operation of thepiston and cylinder mechanisms in sequence or in unison depending on themode of operation desired.

According to one preferred embodiment of the present invention, thesignal valve includes a housing which is mounted at one end of acylinder having a piston movable therein and having first and secondports in the side wall of the cylinder near one end of the cylinder. Thefirst port is located at a point spaced from the one end of the cylinderand the second port is located at a point adjacent the one end of thecylinder. The housing has a first passageway which communicates at afirst end thereof with the first port and a second end which is adaptedto communicate the first passageway with a fluid pressure sensingdevice, such as a whistle. The housing also has a second passagewaywhich has a first end communicating with the interior of the cylinderthrough the second port and a second end which terminates within thehousing. A valve member is positioned within a cavity in the housing,has a first and a second end, and is movable within the housing to andfrom a passageway closing position where the first end of the valvemember closes the first passageway to block the flow of fluid from thecylinder to the second end of the first passageway. The cavitycommunicates with the second end of the second passageway so that fluidin the second passageway acts against the second end of the valvemember. Moreover, the second end of the valve member is designed topresent a larger surface area to fluid acting thereon than is presentedby the first end so that when the fluid pressure in both passageways issubstantially the same, the force on the second end of the valve memberis greater than the force on the first end to bias the valve member tothe passageway closing position. However, when the fluid pressure in thefirst passageway is significantly greater than the fluid pressure in thesecond passageway by reason of the piston having been moved by thepressure of the operating fluid acting thereon to a position between thefirst and second ports, and the movement of the piston is stopped inthis position, the first end of the valve member is moved away from thefirst passageway so that the pressure of the operating fluid iscommunicated through the first passageway to the second end thereof toallow the pressure of the operating fluid to provide a fluid pressuresignal indicating that the piston is at the one end of the cylinder.

An important object of the present invention is to provide a strokesignal valve which will indicate the completion of a stroke of a pistonin a cylinder.

Another object of the present invention is to provide a signal valvewhich will apply the pressure of the operating fluid in a piston andcylinder mechanism to a pressure sensing device when the piston in thecylinder completes a forward stroke and is then at one end of thecylinder, and which will relieve the pressure from the pressure sensingdevice when the piston leaves the one end of the cylinder at thebeginning of a return stroke.

Another object of the present invention is to provide a signal valve forindicating when a piston movable in a cylinder is at one end of thecylinder and which is adapted to operate a fluid operated pilot valve, asmall fluid actuated piston and cylinder mechanism, or a fluid operatedpilot switch.

Another object of the present invention is to provide a signal valve ateach end of a cylinder of a piston and cylinder mechanism in combinationwith a double acting pilot valve for controlling the flow of fluid toeither end of the cylinder to cause oscillation of the piston of themechanism.

Another object of the present invention is to provide individual signalvalves for each one of a group of cylinders having pistons movabletherein, the signal valves being adapted to indicate, by means of afluid pressure signal, when the piston in each cylinder is moved to oneend of the cylinder, and the fluid pressure signal is adapted to beutilized in a fluidic logic control circuit for operating main valvescontrolling the flow of operating fluid to either end of the cylinder tomove the piston in each cylinder from one end to the other end of eachcylinder in sequence or in unison.

Another object of the present invention is to provide a signal valve inwhich movement of a valve member is controlled by fluid pressure actingon each end of the valve member and the valve member is designed topresent a larger surface area at one end thereof to the fluid actingthereon than is presented by the other end so that, when substantiallythe same fluid pressure is applied to both ends of the valve member, theforce acting on the end is greater than the force acting on the otherend to bias the valve member toward the other end.

Another object of the present invention is to provide a signal valvewhich is operated by fluid flowing through ports or holes in the sidewall of a cylinder to indicate the piston of a piston movable in thecylinder.

Still another object of the present in invention is to provide a signalvalve which is adapted for easy mounting on a cylinder of a fluidoperated piston and cylinder mechanism and which requires no externalsource of pressure for the operation thereof.

These and other objects and advantages of the present inventionincluding the manner of their attainment, will become more apparent fromthe following detailed description of a preferred embodiment of theinvention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a sectional view of the signal view of the present inventionmounted on one end of a piston and a cylinder mechanism and showing thepiston of the mechanism situated in an intermediate position between theends of the cylinder; and,

FIG. 2 is a sectional view, similar to FIG. 1, and showing the pistonsituated at one end of the cylinder.

Referring now to the drawings in greater detail, a piston and cylindermechanism is generally indicated at 10 in FIGS. 1 and 2. The mechanism10 includes a cylinder 12 having a cylindrical side wall portion 13 andtwo end caps 14 and 15. The end cap 14 closes one end 16 of the cylinder12 and the end cap 15 closes the opposite end 20 of the cylinder. Apiston rod 22 is received through an opening 24 in the end cap 14 and issuitably joumaled in a bearing 26 mounted in a bore 28 in the end cap14. A suitable seal 30 is positioned in the bore 28 between the bearing26 and the opening 24 to seal the cylinder from the ambient atmosphere.

A piston 32 is situated within the cylinder 12 and is connected by across pin 34 to the end 36 of the piston rod 22 received in the cylinder12. The piston 32 is provided with suitable seals 38 and 40 on the outerperiphery thereof for sealing the rod side 42 of the piston .32 from theother side 44 of the piston.

The end cap 14 has a port opening 46 which is adapted for connection toa fluid line (not shown) which supplies and relieves pressurized fluidto and from the interior of the cylinder 12 through the port opening 46and an internal bore 48 in the end cap 114. In like manner, the end cap15 has a port opening 50 adapted to connect with a fluid line (notshown) for supplying and relieving pressurized fluid to and from thecylinder 12 through the port opening 50 and a bore 52 in the end cap 15.With this arrangement, pressurized fluid can be applied to one side 42or 44 of the piston 32 while pressurized fluid is relieved from theother side 44 or 42 of the piston 32. The piston and cylinder mechanismconstruction described so far is conventional and forms no part of thepresent invention.

The signal valve of the present invention is generally indicated at 54and is mounted on the one end 16 of the cylinder 12. To enable the valve54 to be operated by the operating fluid used to move the piston 32, theside wall 13 of the cylinder 12 is provided with a first port or hole 56which is located at a point spaced from the end 16 of the cylinder 12and a second port or hole 58 which is located at a point adjacent theend 16 of the cylinder 12. Also, the surface 60 of the end cap 14 withinthe cylinder 12 has a slot 62 which is located near the second port 58.The slot 62 is adapted to communicate the port 58 with the internal bore48 and the port opening 56 for relieving fluid pressure from, orapplying fluid pressure to, the port 58 when the piston 32 has beenmoved to the end 16 of the cylinder 12 with the rod side 42 of thepiston 32 flush against the inner surface 60 of the end cap 14. Thesignal valve 54 is adapted to utilize the fluid pressure applied throughthe ports 56 and 58 to indicate the position of the piston 32 in thecylinder 12. More specifically, the signal valve 54 will produce asignal in the form of fluid pressure to indicate when the piston 32 hasbeen moved, by the pressure of the operating fluid acting on the otherside 44 of the piston, to the one end 16 of the cylinder 12 as shown inFIG. 2.

The signal valve 54 includes a housing 64 which is secured by a suitablefastener 65 to the end cap 14. The housing 64 has four passages orpassageways 66-69 formed therein. The first passage 66 has a first end70 in registry with the port 56 and a second end 72 which terminateswithin the housing 64. The second passage is spaced from the firstpassage and has a first end 76 in registry with the second port 58 and asecond end 78 which terminates within the housing 64. As shown, rings 80and 82 are positioned between the housing 64 and the cylinder 12 toprovide a seal at the points of registry between the ports 56 and 58 andthe passages 66 and 67.

The third passage 68 has a first end 86 which is adapted for connectionto a fluid line 88 leading to a fluid pressure sensing device generallyindicated with phantom lines at 89 and a second end 90 terminatingwithin the housing 64. An opening 91 is provided in the housing 64between the second end 72 of the first passage 66 and the second end 90of the third passage 68.

The housing 64 also has a stepped bore 92 in which an insert 94 isreceived. The insert 94 has an internal cavity 96 in which a valvemember 98 is positioned. One end 99 of the insert 94 has an opening 100for communicating one end 101 of the cavity 96 with the second end 90 ofthe third passage 68. As shown, the valve member 98 has a stern portion102 at a first end 103 thereof which extends through the opening 100into the second end 90 of the third passage 68. The opposite or secondend 104 of the cavity 96 is larger than the first end 101 andcommunicates with the second end 78 of the second passage 67. Anelastomeric ball seal 106 is fitted on the stem portion 102 and ispositioned for movement in and transverse ly of the second end 90 of thethird passage 68 to open and close the opening 91 between the firstpassage 66 and the third passage 68 and to close and open the opening100 between the third passage 68 and the cavity 96 in the insert 94.

As shown, a second end 108 of the valve member 98 has a reduced diameterportion 109 which mounts and locates a flexible diaphragm 110 on thevalve member 98 and within the enlarged end 104 of the cavity. It is tobe noted that the outer periphery of the diaphragm 110 is not clamped sothat the diaphragm 110 is allowed to float freely in the enlarged end104 and thereby permit flexing of the diaphragm at low pressuredifferentials.

The second or enlarged end 104 of the cavity 96 is defined by a steppedbore portion in the insert 94 and the diaphragm 110 is received in thespace formed by the smallest radius annular step 113. A portion 113a ofthe annular step 113 tapers toward the portion of the cavity 96 whichslidably receives the valve member 98. In this way, a frustoconicalspace is provided in which the diaphragm 110 can flex. The larger radiusannular step 114 receives and holds a washer 116 press fitted thereinsuch that the washer 116 holds the diaphragm 110 within the annular step113. When the valve member 98 is moved to open the opening 91 betweenthe first passage 66 and the third passage 68, the diaphragm 110 ismoved against the washer 116 and the washer 116 serves to straighten anyconical set that may have developed in the diaphragm 110 when the valvemember 110 was in a position closing the opening 91 between the firstpassage 66 and the third passage 68.

The fourth or vent passage 69 is defined by an aperture 118 in thehousing 64, radial apertures 120 in the insert 94, the end 101 of thecavity 96 and the opening in the one end 99 of the insert. When thevalve member 98 is in the position shown in FIG. 1, the third passage 68is vented by the fourth passage 69 to atmosphere, or to a reservoirconnected to the aperture 118, via the opening 100, the cavity 96, theradial apertures 120 and the aperture 118.

Referring now to the operation of the signal valve 54, it will beunderstood that various fluids, e.g., a gas or a liquid, can be used forthe operating fluid in the piston and cylinder mechanism 10 so that thesignal valve 54 can be utilized with either a pneumatic or a hydraulicmechanism 10. However, when compressed air is used as the operatingfluid, a special reservoir is not required for the air vented throughthe fourth passage 69. Therefore, the operation of the signal valve 54will now be described when used on a pneumatically operated piston andcylinder mechanism 10 in which compressed air is utilized for theoperating fluid.

When the piston is in the position shown in FIG. 1, the valve 54 isclosed by reason of the elastomeric ball seal 106 closing the opening 91between the first passage 66 and the third passage 68. In this positionof the piston 32, it will be noted that the pressure of the fluid on therod side 42 of the piston 32 is applied through both ports 56 and 58 tothe first and second ends 103 and 108 of the valve member 98. With thediaphragm at the second end 108 presenting a larger surface area to thefluid acting on the second end 108 than is presented by the first end103 to the fluid acting thereon, i.e., than by the portion of the ballseal 106 facing the opening 91, the force on the second end 108 of thevalve member 98 tending to move the valve member 98 to the left isgreater than the force on the first end 103 of the valve member 98tending to move it to the right. Consequently, the valve member 98 isbiased to the left to a closed position where the ball seal 106 at thefirst end 103 closes the opening 91 between the first passage 66 and thethird passage 68.

It will be understood that the piston 32 will be in the position shownin FIG. 1 during a return stroke of the piston 32 toward the end cap 15and during a forward stroke of the piston 32 toward the end cap 14. On areturn stroke, pressurized air is admitted through the port opening 46to the interior of the cylinder on the rod side 42 of the piston 32 andforces the piston 32 toward the end cap 15. Of course, at the same time,the fluid line connected to the port opening 50 in the end cap 15 isvented to atmosphere. At this time, the pressure in the cylinder 12between the rod side 42 of the piston 32 and the inner surface 60 of theend cap 14 is greater than atmospheric pressure. However, since the samepressure is applied to both ends 103 and 108 of the valve member 98through ports 56 and 58 and passages 66 and 67, a greater force isdeveloped at the second end 108 as described above, and this force holdsthe valve member 98 in the closed" position.

After the piston 32 reaches the second end 20 of the cylinder 12, theair line leading to the port opening 46 is vented to atmosphere and airpressure is now applied through the port opening 50 to the other side 44of the piston 32 so that the piston 32 is forced to the right toward theend cap 14. When this occurs, the pressure of the air on the other side44 of the piston 32 will be greater than the pressure of the air beingforced out of the cylinder 12 through the port opening 46. However, thispressure of the air on the rod side 42 of the piston 32 is applied toboth ends 103 and 108 of the valve member 98 through the ports 56 and58, and the valve member 98 will remain in the closed position by reasonof the larger force acting at the second end 108 of the valve member 98,at least until the piston 32 is moved to the end 16 of the cylinder 12as shown in FIG. 2.

When the piston 32 completes its forward stroke and is at the one end 16of the cylinder 12, the periphery of the piston 32 is situated betweenthe first port 56 and the second port 58, and the greater air pressureon the other side 44 of the piston 32 is now communicated through theport 56 and the first passage 66 to the ball seal 106 at the first end103 of the valve member 98. At the same time, any air pressure on therod side 42 of the piston 32 is relieved from the cylinder 12 via theslot 62, the bore 48 and the port opening 46. Since the pressure of theair acting on the other side 44 of the piston is much greater thanatmospheric pressure, a force is now established at the first end 103 ofthe valve member 98 which is greater than the force on the second end108 of the valve member 98 to cause movement of the valve member 98 toan open position where the opening 91 between the first passage 66 andthe third passage 68 is open to allow the pressurized air to flowthrough the first and third passages 66 and 68 to the fluid line 88. Atthe same time, the elastomeric ball seal closes the opening 100 in theinsert 94 to close the fourth passage 69 which normally vents the thirdpassage 68 to atmosphere.

In one embodiment of the signal valve of the present invention, device89 is a whistle or other fluid actuated sound producing device so thatthe pressurized air which flows to the line 88, when the piston 32 is atthe one end 16 of the cylinder 12, will act upon the whistle or othersound producin device to produce a sound which indicates that the pistonis at the one end 16 of the cylinder 12. In this position of the valvemember 98, the diaphragm 110 is positioned in a plane parallel to theplane of the washer 116 and the second passage 67 is vented toatmosphere via the second port 58, the slot 62, the bore 48 and the portopening 46.

When the control valve (not shown) controlling the flow of compressedair to the cylinder and piston mechanism is operated to connect thefluid line leading to the port opening 50 to atmosphere and to connectthe fluid line 46 leading to the port opening 46 to the source (notshown) of compressed air, the fluid pressure acting on the second end108 of the valve member 98 will be greater than the fluid pressureacting on the first end 103 such that the valve member 98 is moved fromthe open position to the closed" position where the elastomeric ballseal 106 closes the opening 91 and vents the third passage 68 toatmosphere via the fourth passage 69. After the piston 32 is moved pastthe first port 56, to the position shown in FIG. 1, the fluid pressureacting on both ends 103 and 108 of the valve member 98 will be the same.Accordingly, the force on the second end 108 of the valve member 98 willbe greater than the force on the first end 103, as described above, sothat the valve member 98 remains in the closed position as shown in FIG.1, until the position 32 is returned to the one end 16 of the cylinder12.

It will be understood from the above description of the operation of thesignal valve 54, that every time the piston 32 is moved to the one end16 of cylinder 12, as shown in FIG. 2, the pressure of the operatingfluid admitted to the port 56 will cause the valve member 98 to move toits open position to apply the pressure of the operating fluid, such asair, to the fluid line 88. Although, in one embodiment of the invention,the device 89 is a whistle, it is to be understood that the device 89can be a double acting pilot valve which will operate a main valve (notshown) controlling the flow of pressurized fluid to the port openings 46and 50. In such a modified embodiment of the invention, another signalvalve is mounted at the other end 20 of the cylinder 12 in a similarmanner to the valve 54 at the end 16, so that, when the piston 32reaches the other end 20, the signal valve at the end 20 is opened tooperate the pilot valve to operate the main valve to vent the portopening 46 to atmosphere and to supply pressurized fluid to the portopening 50 to initiate the forward stroke of the piston. Then,

when the piston 32 advances to the one end 16 of the cylinder.

12, the signal valve 54 is opened" to cause the pilot valve to operatethe main valve to vent the fluid line connected to the port opening 50and to supply pressurized fluid to the fluid line leading to the portopening 46. In this way. reciprocation of the piston 32 can becontrolled by the signal valves mounted at each end of the cylinder 12in combination with the pilot valve and the main valve.

In another embodiment of the invention, individual signal valves areprovided at each end of each cylinder in a group of piston and cylindermechanisms. The fluid lines, correspond ing to the fluid line 88 inFIGS. 1 and 2, from each signal valve are connected to a fluidic logiccontrol circuit which is adapted to control the flow of pressurizedfluid to the first and second ends of'each cylinder. In this way, thepistons in each one of the piston and cylinder mechanisms can beoperated in unison or in sequence, depending upon the mode of operationdesired.

It is to be understood from the foregoing description that the presentinvention provides a signal valve which indicates, in the form of afluid pressure signal, when a piston is at the end of a forward orreturn stroke in a cylinder. Furthermore, the signal valve is adapted tostop the fluid pressure signal when the piston leaves the end of thecylinder as it begins a return or forward stroke.

Accordingly, the signal valve of the present invention has a number ofadvantages, some of which are as follows:

1. The fluid pressure signal can be utilized to operate a number offluid operated devices, such as an air operated pilot valve, a small airpiston and cylinder mechanism, or an air operated pilot switch.

2. Individual signal valves can be mounted on each end of a cylinder andthe fluid line from each valve can be connected to a double acting pilotvalve for controlling the flow of compressed air to the cylinder tocause oscillation of the piston in the cylinder.

3. A group ofcylinders, each with an individual signal valve at each endof each cylinder, can be utilized in combination with a fluidic logiccontrol circuit to operate the pistons in each cylinder in sequence orin unison, depending upon the operation desired.

4. The signal valve utilizes an unbalance of the forces acting on eachend of the valve member to keep the valve closed when pressure at bothends of the valve member is substantially equal and permits the valvemember to open the valve when pressure is relieved from the second ordiaphragm end of the valve member.

5. The utilization of spaced apart ports at one end of a cylinder in apiston and cylinder mechanism enables the signal valve to be easilyadapted for use with an existing piston and cylinder mechanism merely byforming two small holes in the cylinder side wall to form the first and]second ports 56 and 58.

6. The signal valve is operated by the pressure of the operating fluidused to move the piston within the cylinder so that the signal valverequires no external source of fluid pressure.

7. The simple mounting of the signal valve by means of one fastenerenables the signal valve to be easily removed for maintanence andrepair.

Thus, the signal valve of the present invention has numerous advantagesand applications some of which have been described aboveand others whichare inherent in the invention. Consequently, the scope of the presentinvention is only to be limited as necessitated by the accompanyingclaims.

I claim:

l. A signal valve in combination with a cylinder and piston forproducing a signal in the form of fluid pressure to indicate when saidpiston, movable in said cylinder, is moved by the pressure of anoperating fluid to one end of said cylinder, said cylinder having meansat each end for admitting and relieving fluid to and from said cylinderand having in the side wall thereof a first port located at a pointspaced from said one end of said cylinder and a second port located at apoint adjacent said one end of said cylinder, said signal valveincluding a housing mounted on said cylinder adjacent said one end ofsaid cylinder and having a passageway therein which communicates at afirst end with said first port and communicates at a second end withposition indicator means sensing fluid pressure, a movable valve memberreceived within said housing and having a first end and a second end andbeing movable to and from a passageway closing position where said firstend closes said passageway, a passage in said housing communicating at afirst end with said second port and at a second end with said second endof said valve member, said second end of said valve member having meansfor presenting a larger surface area to the fluid acting thereon thansaid first end so that when the same pressure is acting on both ends ofsaid valve member, the force of said fluid acting on said second end isgreater than the force acting on said first end to bias said valvemember toward said passageway closing position to close said passagewayuntil said piston is moved by said operating fluid to a position betweensaid first and second ports where said pressure of said operating fluidacting on said piston is communicated through said first port and saidpassageway to said first end of said valve member to establish a forceat said first end of said valve member which is greater than the forceat said second end to move said valve member away from said passagewayclosing position to allow said operating fluid to flow through saidpassageway to establish a fluid pressure signal at said second end ofsaid passageway indicating that said piston is at said one end of saidcylinder, said housing having a vent passage therein, one end of whichterminates within said housing, and said housing having an openingbetween said passageway and said one end of said vent passage, saidopening being closed by said first end of said valve member when saidpiston is at said position between said first and second ports, andbeing opened to communicate said second end of said passageway with saidvent passage for venting said second end of said passageway when saidvalve member is in said passageway closing position.

2. A signal valve as defined in claim 1 wherein said second end of saidvalve member has a flexible diaphragm mounted thereon, said diaphragmforming said means for defining said larger surface area at said secondend of said valve member.

3. A system for indicating when a piston, movable in a cylinder, ismoved by the pressure of an operating fluid to one end of the cylinder,said cylinder having means at each end for admitting and relieving fluidto and from said cylinder and having first and second ports in the sidewall thereof, said first port being located at a point spaced from oneend of said cylinder and said second port being located at a pointadjacent said one end of said cylinder, said system comprising a signalvalve and a fluid pressure sensing means connected to said valve fortransducing a fluid pressure signal to a sound for acousticallyindicating the position of said piston at said one end of said cylinder,and said signal valve including a housing mounted at said one end ofsaid cylinder and having first and second passages, each of saidpassages having a first end communicating with the interior of saidcylinder through said first and second ports, respectively, and a secondend terminating at a point within said housing, a third passage in saidhousing having one end in communication with said fluid pressure sensingmeans and a second end terminating at a point within said housing, saidhousing having an opening between said second end of said first passageand said second end of said third passage and having an interior cavitywith a first end which is in communication with said second ends of saidfirst and third passages and an enlarged second end which is incommunication with said second end of said second passage, a movablevalve member situated in said cavity and having a first end which isadapted to close said opening between said second ends of said first andthird passages, and a second end positioned in said enlarged end of saidcavity, said second end of said valve member having means for presentinga larger surface area to fluid acting thereon than is presented by saidfirst end whereby, when said first passage and said second passage areboth in communication with the fluid in said cylinder between one sideof said piston and said one end of said cylinder through said first andsecond ports, the force on said valve member at said second end isgreater than the force at said first end to bias said first end of saidvalve member toward said opening between said first passage and saidthird passage to close said opening until said piston is moved by thepressure of the operating fluid acting on the other side of said pistonto a position between said first and second ports where said pressure ofsaid operating fluid on said other side of said piston is communicatedthrough said first port and said first passage to said first of saidvalve member to establish a force at said first end of said valve memberwhich is greater than said force at said second end to move said firstend of said valve member away from said opening to allow said operatingfluid on said other side of said piston to flow through said first andthird passages to supply a fluid pressure signal to said fluid pressuresensing means which then produces a sound indicating that said piston isat said one end of said cylinder.

4. A system for indicating when a piston, movable in a cylinder, ismoved by the pressure of an operating fluid to one end of the cylinder,said cylinder having means at each end for admitting and relieving fluidto and from said cylinder and having first and second ports in the sidewall thereof, said first port being located at a point spaced from oneend of said cylinder and said second port being located at a pointadjacent said one end of said cylinder, said system comprising a signalvalve and a fluid pressure sensing means connected to said valve fortransducing a fluid pressure signal to a sound for acousticallyindicating the position of said piston at said one end of said cylinder,and said signal valve including a housing mounted at said one end ofsaid cylinder and having first and second passages, each of saidpassages having a first end communicating with the interior of saidcylinder through said first and second ports, respectively, and a secondend terminating at a point within said housing, a third passage in saidhousing having one end in communication with said fluid pressure sensingmeans and a second end terminating at a point within said housing, saidhousing having an opening between said second end of said first passageand said second end of said third passage and having an interior cavitywith a first end which is in communication with said second ends of saidfirst and third passages and an enlarged second end which is incommunication with said second end of said second passage, a movablevalve member situated in said cavity and having a first end which isadapted to close said opening between said second ends of said first andthird passages, and a second end positioned in said enlarged end of saidcavity, said second end of said valve member having a diaphragm mountedthereon for presenting a larger surface area to fluid acting thereonthan is presented by said first end whereby, when said first passage andsaid second passage are both in communication with the fluid in saidcylinder between one side of said piston and said one end of saidcylinder through said first and second ports, the force on said valvemember at said second end is greater than the force at said first end tobias said first end of said valve member toward said opening betweensaid first passage and said third passage to close said opening untilsaid piston is moved by the pressure of the operating fluid acting onthe other side of said piston to a position between said first andsecond ports where said pressure of said operating fluid on said otherside of said piston is communicated through said first port and saidfirst passage to said first end of said valve member to establish aforce at said first end of said valve member which is greater than saidforce at said second end to LII third passage and said vent passage,said second opening being closed by said first end of said valve memberwhen said piston is at said position between said first and secondports, and being opened to communicate said third passage with said ventpassage for venting said third passage when said valve member is in aposition closing the opening between said first passage and said thirdpassage.

UNITED STATES TATTNT nTTTtT @ERTH'TCATE F QREQTEN Patent No. 3,6n8,568Dated March 1 4-, 1972 Inventor(s) Lee A Wright It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 39, insert the word "end" after the word "first" at theend of the line.

Column 2, line 34, the word "piston" should be --positi0n--.

Column 2, line 36, delete the word "in".

Column 8, line 20, insert the word "end" after the word "first" in thefirst instance.

Signed and sealed this 5th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-1050 (10-69) USCOMM-DC 6O376-P69 ucs. GOVERNMENTPRINTING OFFICE: 1959 o-ase-aas

1. A signal valve in combination with a cylinder and piston forproducing a signal in the form of fluid pressure to indicate when saidpiston, movable in said cylinder, is moved by the pressure of anoperating fluid to one end of said cylinder, said cylinder having meansat each end for admitting and relieving fluid to and from said cylinderand having in the side wall thereof a first port located at a pointspaced from said one end of Said cylinder and a second port located at apoint adjacent said one end of said cylinder, said signal valveincluding a housing mounted on said cylinder adjacent said one end ofsaid cylinder and having a passageway therein which communicates at afirst end with said first port and communicates at a second end withposition indicator means sensing fluid pressure, a movable valve memberreceived within said housing and having a first end and a second end andbeing movable to and from a passageway closing position where said firstend closes said passageway, a passage in said housing communicating at afirst end with said second port and at a second end with said second endof said valve member, said second end of said valve member having meansfor presenting a larger surface area to the fluid acting thereon thansaid first end so that when the same pressure is acting on both ends ofsaid valve member, the force of said fluid acting on said second end isgreater than the force acting on said first end to bias said valvemember toward said passageway closing position to close said passagewayuntil said piston is moved by said operating fluid to a position betweensaid first and second ports where said pressure of said operating fluidacting on said piston is communicated through said first port and saidpassageway to said first end of said valve member to establish a forceat said first end of said valve member which is greater than the forceat said second end to move said valve member away from said passagewayclosing position to allow said operating fluid to flow through saidpassageway to establish a fluid pressure signal at said second end ofsaid passageway indicating that said piston is at said one end of saidcylinder, said housing having a vent passage therein, one end of whichterminates within said housing, and said housing having an openingbetween said passageway and said one end of said vent passage, saidopening being closed by said first end of said valve member when saidpiston is at said position between said first and second ports, andbeing opened to communicate said second end of said passageway with saidvent passage for venting said second end of said passageway when saidvalve member is in said passageway closing position.
 2. A signal valveas defined in claim 1 wherein said second end of said valve member has aflexible diaphragm mounted thereon, said diaphragm forming said meansfor defining said larger surface area at said second end of said valvemember.
 3. A system for indicating when a piston, movable in a cylinder,is moved by the pressure of an operating fluid to one end of thecylinder, said cylinder having means at each end for admitting andrelieving fluid to and from said cylinder and having first and secondports in the side wall thereof, said first port being located at a pointspaced from one end of said cylinder and said second port being locatedat a point adjacent said one end of said cylinder, said systemcomprising a signal valve and a fluid pressure sensing means connectedto said valve for transducing a fluid pressure signal to a sound foracoustically indicating the position of said piston at said one end ofsaid cylinder, and said signal valve including a housing mounted at saidone end of said cylinder and having first and second passages, each ofsaid passages having a first end communicating with the interior of saidcylinder through said first and second ports, respectively, and a secondend terminating at a point within said housing, a third passage in saidhousing having one end in communication with said fluid pressure sensingmeans and a second end terminating at a point within said housing, saidhousing having an opening between said second end of said first passageand said second end of said third passage and having an interior cavitywith a first end which is in communication with said second ends of saidfirst and third passages and an enlarged second end which is incommunication with said second end of said sEcond passage, a movablevalve member situated in said cavity and having a first end which isadapted to close said opening between said second ends of said first andthird passages, and a second end positioned in said enlarged end of saidcavity, said second end of said valve member having means for presentinga larger surface area to fluid acting thereon than is presented by saidfirst end whereby, when said first passage and said second passage areboth in communication with the fluid in said cylinder between one sideof said piston and said one end of said cylinder through said first andsecond ports, the force on said valve member at said second end isgreater than the force at said first end to bias said first end of saidvalve member toward said opening between said first passage and saidthird passage to close said opening until said piston is moved by thepressure of the operating fluid acting on the other side of said pistonto a position between said first and second ports where said pressure ofsaid operating fluid on said other side of said piston is communicatedthrough said first port and said first passage to said first end of saidvalve member to establish a force at said first end of said valve memberwhich is greater than said force at said second end to move said firstend of said valve member away from said opening to allow said operatingfluid on said other side of said piston to flow through said first andthird passages to supply a fluid pressure signal to said fluid pressuresensing means which then produces a sound indicating that said piston isat said one end of said cylinder.
 4. A system for indicating when apiston, movable in a cylinder, is moved by the pressure of an operatingfluid to one end of the cylinder, said cylinder having means at each endfor admitting and relieving fluid to and from said cylinder and havingfirst and second ports in the side wall thereof, said first port beinglocated at a point spaced from one end of said cylinder and said secondport being located at a point adjacent said one end of said cylinder,said system comprising a signal valve and a fluid pressure sensing meansconnected to said valve for transducing a fluid pressure signal to asound for acoustically indicating the position of said piston at saidone end of said cylinder, and said signal valve including a housingmounted at said one end of said cylinder and having first and secondpassages, each of said passages having a first end communicating withthe interior of said cylinder through said first and second ports,respectively, and a second end terminating at a point within saidhousing, a third passage in said housing having one end in communicationwith said fluid pressure sensing means and a second end terminating at apoint within said housing, said housing having an opening between saidsecond end of said first passage and said second end of said thirdpassage and having an interior cavity with a first end which is incommunication with said second ends of said first and third passages andan enlarged second end which is in communication with said second end ofsaid second passage, a movable valve member situated in said cavity andhaving a first end which is adapted to close said opening between saidsecond ends of said first and third passages, and a second endpositioned in said enlarged end of said cavity, said second end of saidvalve member having a diaphragm mounted thereon for presenting a largersurface area to fluid acting thereon than is presented by said first endwhereby, when said first passage and said second passage are both incommunication with the fluid in said cylinder between one side of saidpiston and said one end of said cylinder through said first and secondports, the force on said valve member at said second end is greater thanthe force at said first end to bias said first end of said valve membertoward said opening between said first passage and said third passage toclose said opening until said piston is moved by the presSure of theoperating fluid acting on the other side of said piston to a positionbetween said first and second ports where said pressure of saidoperating fluid on said other side of said piston is communicatedthrough said first port and said first passage to said first end of saidvalve member to establish a force at said first end of said valve memberwhich is greater than said force at said second end to move said firstend of said valve member away from said opening to allow said operatingfluid on said other side of said piston to flow through said first andthird passages to supply a fluid pressure signal to said fluid pressuresensing means which then produces a sound indicating that said piston isat said one end of said cylinder, said housing having a vent passagetherein one end of which terminates within said housing, and saidhousing having a second opening therein between said third passage andsaid vent passage, said second opening being closed by said first end ofsaid valve member when said piston is at said position between saidfirst and second ports, and being opened to communicate said thirdpassage with said vent passage for venting said third passage when saidvalve member is in a position closing the opening between said firstpassage and said third passage.